**1. Introduction**

20 Will-be-set-by-IN-TECH

*Japan Synchrotron Radiation Research Institute, SPring-8, 1-1-1 Kouto, Mikazuki-cho, Sayo-gun,*

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**7. References**

High-throughput protein crystallography can be a time consuming and resource intensive endeavor. Although recent years have seen many advances in the field, screening for suitable crystallization conditions using common commercially available platforms still requires considerable amounts of protein and reagents. Furthermore, diffraction quality testing and data collection typically involve physical extraction and cryogenic freezing of the crystal samples, which may have a significant impact on the integrity of the crystal (Garman, 1999). To acquire high-quality diffraction data, both the crystallization conditions and the cryoprotectants must be further optimized. These steps can be time consuming and are often restricted to experienced users (Alcorn & Juers, 2010). In response to these concerns, the last decade has seen a significant surge of developments in crystallographyaimed microtechnology, specifically the use of crystallization chips. So far, the field is dominated by a range of microfluidic devices (Li & Ismagilov, 2010), with one of the most significant differences between them being the type of crystallization technique they employ. Several devices have been developed, and even commercialized (Topaz® crystallizer, Fluidigm Corp., CA, USA; The Crystal Former, Microlytic Inc., MA, USA) that utilize free interface diffusion (FID) (Hansen *et al.*, 2002). Other chips employ nanochannels to create counter-diffusion crystallization (Hasegawa *et al.,* 2007, Ng *et al.*, 2008, Dhouib *et al.*, 2009) or nanodroplets that simulate batch crystallization (Zheng *et al.*, 2003). There are two clear, parallel implications in all these devices. They are all striving to increase efficiency of the hit identification process, and are offering the possibility of *in situ* X-ray analysis and, in favorable cases, diffraction data collection for structure determination (Zheng *et al.*, 2004, Hansen *et al.*, 2006, Ng *et al.*, 2008, May *et al,* 2008, Dhouib *et al.*, 2009).

© 2012 Chirgadze et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 Chirgadze et al., licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

The X-CHIP (Chirgadze, 2009) addresses the same challenges of high-throughput crystallography with an alternative approach, and has a number of unique additional advantages. In contrast to microfluidic chips, the crystallization process takes place on the chip surface, in droplet arrays of aqueous protein and crystallization reagents mixtures under a layer of oil. These microbatch arrays are made possible by altering the chip surface with a unique coating, creating defined areas of varying hydrophobicity. This paper presents the design of the device and accompanying tools for setting up crystallization trials and mounting the chip for data collection, as well as the important benefits, limitations and implications that are inherent to this platform. It also describes proof-of-concept experiments in which this technology was utilized for crystal growth, visual inspection, Xray diffraction data collection and structure determination of two native and one selenomethionine-labeled protein targets. The presented results show that large, welldiffracting crystals can be grown and high-quality data sets sufficient for structure determination can be collected on a home as well as a synchrotron X-ray source.
